Method of providing tubular lamps



June 6, 19%? c. PRUN METHOD OF PROVIDING TUBULAR LAMPS Filed Jan. 6, 1964 INVENTOR.

CORNELI S PRIJ N AGENT United States Patent 3,323,855 METHOD OF PROVIDING TUBULAR LAMPS Cornelis Prijn, Emmasingel, Eindhoven, Netherlands, as-

signor to North American Philips Company, Inc, New York, N .Y., a corporation of Delaware Filed Jan. 6, 1964, Ser. No. 335,867 Claims priority, application Netherlands, Jan. 24, 1963, 288,161 3 Claims. (Ci. 316-17) A method is known for providing a tubular lamp with two relatively adjusted reference means, such as apertures, one of which is situated on each tongue-shaped projection extending in the longitudinal direction of the lamp and forming part of a lamp cap fixed on one end of the lamp.

In this known construction the apertures serving as reference means are already present in the tongue-shaped projections before the lamp cap is definitely fixed on the lamp vessel. The method employed for fixing the lamp caps on the lamp vessel can correct in this known lamp only comparatively small manufacturing tolerances of the lamp vessel.

An object of the present invention is to provide an improved method of providing a tubular lamp with two relatively adjusted reference means, the advantage being obtained that the reference means are not only adjusted with respect to each other but also acquire a prescribed position relative to the filament in the lamp. Besides there is the advantage that, in contrast with the known lamp, the lamp caps are rigidly fixed on the ends of the lamp.

To achieve this result, the method according to the present invention is characterized in that, after the lamp caps are rigidly fixed on the ends of the lamp, the reference means, while the filament present in the lamp has been given a prescribed position, are formed in the tongueshaped projections by a chipping operation at areas which have a prescribed position relative to the position of the filament. Proceeding in this way affords the advantage that inaccuracies in the manufacture of the lamp vessel, in the location of the filament inside the bulb and the like cannot affect the quality of the lamp ultimately obtained.

The present invention is applicable not only to tubular incandescent lamps but also to discharge tubes. In the latter case the discharge path fulfils the function of the filament.

The chipping operation usually consists in a drilling or milling operation. As an alternative, however, the apertures may be obtained by a punching operation.

The invention is especially advantageous for lamps of the kind having a comparatively small bulb vessel, such as so-called iodine incandescent lamps. In fact, in certain uses, said lamps are employed in combination with optical means such as a reflector and a lens. It is then very important that the filament in the lamp becomes situated in exactly the prescribed position relative to the optical means.

In order that the invention may be readily carried into effect, it will now be described in detail, by way of example, with reference to the accompanying diagrammatic drawing, in which:

FIGURES 1 and 2 are an elevational view and a side view, respectively, of one embodiment ofthe lamp acice cording to the invention, the reference means, which in this example are in the form of circular apertures, being formed in the tongue-shaped projections forming part of the lamp caps.

The lamp shown in FIGURES 1 and 2 comprises a bulb 10 closed at its end by seals 11 and 12. The bulb made of quartz glass contains a filament 13. The lamp is a socalled iodine incandescent lamp and is filled through an exhaust tube, the sealing tip of which is indicated by 14, with the required gas filling and the ingredients giving off free iodine during operation of the lamp. Each end of the filament 13 is connected through molybdenum foils 15 and 16, respectively, located in the seals 11 and 12, respectively, to external current supply wires 17 and 18 respectively. Each seal is surrounded by a cap 19, 20 respectively, which is formed of a folded metal strip. As may be seen especially from FIGURE 2, each strip is folded at its end at 21 and 22 respectively. The surfaces thus obtained engage the seal on each side. The stripshaped material of each cap is provided with strip-shaped parts located laterally of the seals, each two adjacent stripshaped parts being secured together by a welding or soldering operation. This can be seen from the upper part of FIGURE 2 where the strip-shaped parts facing each other and secured to each other are indicated by 19a and 1%. In this way the lamp cap fits through a sleeve-shaped portion on the seal of the lamp and may be fixed on it with the aid of cement.

It may also be seen from FIGURE 2 that the end of each current supply wire emerging from a seal is led through an aperture (20a) in the cap to the exterior and secured through a bent portion to the material of the cap.

The lamp may be connected to an external currentsupply source through apertures 29 and 30, respectively, in tongue-shaped ends 19c and 200 respectively, extending in the longitudinal direction of the lamp, of the caps 19 and 20 respectively. A structure of the cap is thus obtained which is extremely simple, sturdy and reliable.

According to the invention, the apertures 29 and 30 are not formed in the tongue-shaped ends until the lamp caps 19 and 20 are rigidly fixed on the seals 11 and 12 respectively. For this purpose one proceeds, for example, as follows: The filament 13 is switched on and projected onto a screen by means of an optical system. Next, the lamp is displaced by means of a suitable holder until the image of the filament finds itself exactly at a prescribed position on the screen. In this position the holder of the lamp and hence the lamp together with the caps and its tongue-shaped projections 19c and 200 is fixed. Now drills or mills arranged at a prescribed distance from each other and from the filament are moved towards the tongues 19c and 29a and the apertures 29 and 30 formed in said tongues. When proceeding in this Way, then despite possible inaccuracies in the position of the filament relative to the bulb and the caps, there is full certainty that the resulting lamp provided with reference means fully satisfies the requirements to be imposed with regard to the location of the filament relative to the reference means.

What is claimed is:

1. A method of manufacturing an electric lamp comprising the steps of inserting a filament in the lamp bulb, operatively connecting external current supply wires to said filament, filling said lamp bulb with a gas through an exhaust tube, sealing off said exhaust tube, rigidly fixing a lamp 'cap havingtongue shapedprojections thereon to each end of the lamp bulb, said tongue-shaped projections extending along the longitudial axis of said lamp bulb, displacing the lamp until the filament is located in a predetermined position, and forming reference means in said tongue-shaped projections by cutting into areas thereof Which-have a prescribed location relative to the position of said filament.

2. A method of 'manufacturing an electric lamp as claimed in claim-1 wherein said reference means are produced by cutting through said projections to form apertures. v i

3. A method of manufacturing an electric lamp as tongue-shaped projection thereon is formed by folding a metal strip and securing the folded-over parts of said tongue-shaped projection together.

References Cited UNITED STATES PATENTS RICHARD H. EANES, JR., Primary Examiner.

claimed in claim 1 wherein each of said lamp caps and 15 DAV GALVIN, Examiner- 

1. A METHOD OF MANUFACTURING AN ELECTRIC LAMP COMPRISING THE STEPS OF INSERTING A FILAMENT IN THE LAMP BULB, OPERATIVELY CONNECTING EXTERNAL CURRENT SUPPLY WIRES TO SAID FILAMENT, FILLING SAID LAMP BULB WITH A GAS THROUGH AN EXHAUST TUBE, SEALING OFF SAID EXHAUST TUBE, RIGIDLY FIXING A LAMP CAP HAVING TONGUE-SHAPED PROJECTIONS THEREON TO EACH END OF THE LAMP BULB, SAID TONGUE-SHAPED PROJECTIONS EXTENDING ALONG THE LONGITUDINAL AXIS OF SAID LAMP BULB, DISPLACING THE LAMP UNTIL THE FILAMENT IS LOCATED IN A PRE- 